JPH1155539A - Image processing method and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an output that is seen closer to 'two colors' by improving the reproducibility of a 2-color print original or to enhance the convenience of the user by outputting a print at a high speed as required. SOLUTION: The system is provided with an image edit section 311 in addition to a function of a general color copying machine, uses an RGB→HSL conversion section 308 to apply RGB→HSL conversion to an input image (Hin, Sin, Lin) and an arithmetic processing section 309 converts the input image into an image expressed in 2-color contrast by arithmetic processing. Then an HSL→RGB conversion section 310 applies HSL→RGB conversion to the image to decode it into RGB data again and the system prints out an image expressed in 2-color contrast.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus for processing a color image.

[0002]

2. Description of the Related Art In recent years, image processing apparatuses for handling full-color images, such as digital color copying machines, have been widely used. In these apparatuses, when a color image is printed out on a recording paper or the like, the red (R), green (G), and blue (B) images read by a scanner or the like are usually converted to cyan (C), Full-color printing is reproduced by converting the image into a three-color image of magenta (M) and yellow (Y) or a four-color image in which black (Bk) is added thereto, and outputting one color at a time.

[0003]

However, in the above-mentioned conventional example, even in the case of, for example, copying an original printed in two colors of red and black, it is necessary to reproduce subtle colors in full color. May not be obtained.

In addition, "red pen correction" which does not emphasize color reproduction.
For example, a document such as a document is output with the color superimposed four times, so that it takes time to output.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and it is an object of the present invention to improve the reproducibility of a two-color original, for example, and to provide an output that looks more "two colors".

[0006] Alternatively, it is another object of the present invention to output data at a higher speed as needed to improve user convenience.

[0007]

In order to achieve the above object, an embodiment of the present invention has, for example, the following configuration.

That is, conversion means for performing coordinate conversion of an input image signal of a plurality of colors into a signal of a color space comprising three coordinates of hue, saturation, and lightness, and a predetermined arithmetic processing on a signal which has been subjected to coordinate conversion by the conversion means. And a reverse conversion means for performing reverse conversion of a signal processed by the processing means into a signal of an original color space before conversion by the conversion means. It is characterized in that it can be converted into an image represented by color shading.

For example, the processing means is characterized in that the input image can be converted into an image represented by two shades of black and a specified color other than black. Alternatively, the image processing apparatus further includes an output unit that outputs an image in a frame-sequential manner for each color, and the output unit omits a procedure of outputting another unnecessary color component when the processing unit converts the image into a two-color grayscale image. It is characterized in that it is possible.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

(First Embodiment of the Invention) Hereinafter, an embodiment of the invention according to the present invention will be described in detail with reference to the drawings, taking a digital color copying machine as an example.

FIG. 1 is an overall view of a color copying machine according to an embodiment of the present invention. In FIG. 1, reference numeral 201 denotes an image scanner, which reads a document and performs digital signal processing. 500 is a printer unit,
The image processed by the image scanner unit 201 is printed out in full color on recording paper.

In the image scanner section 201, 20
Reference numeral 2 denotes a digitizer also serving as a document pressure plate, which is used to designate a region on the document by placing a document 204 on the digitizer 202 before a copying operation and pressing a desired point with an attached pen. Reference numeral 203 denotes a platen glass (document mounting table), 20
5 is a halogen lamp, 206 and 207 are mirrors, 208
Denotes a lens, 209 denotes a signal processing unit, and 210 denotes a three-line sensor (hereinafter, referred to as “CCD”).

Hereinafter, the operation of the copying machine according to the embodiment of the present invention having the above configuration will be described.

When a document 204 is placed on a platen glass 203 and a start instruction is input from an operation panel (not shown), the document 20 is sequentially operated while the halogen lamp 205 is operated.
Irradiate 4. Light reflected from the original is reflected by mirrors 206 and 20.
The image is formed on a three-line sensor (hereinafter referred to as a CCD) 210 by a lens 208.

The CCD 210 decomposes the light information into three components of red (R), green (G), and blue (B) and sends it to the signal processing unit 209.

The signal processing unit 209 electrically processes the read signal, decomposes the signal into magenta (M), cyan (C), yellow (Y), and black (Bk) density signals and sends the signal to the printer unit 202. . In this example, when the image scanner unit 201 scans the document once, a density signal of one color among M, C, Y, and Bk is sent to the printer 200, and a full-color image is output once in four scans.

[Flow of Image Processing] FIG. 2 is a block diagram showing a detailed configuration of the signal processing unit 209 shown in FIG. 1 according to the embodiment of the present invention.

In the figure, reference numeral 301 denotes a shading correction unit for correcting variations in the sensitivity of the CCD 210 and the amount of light from the halogen lamp 205; and 302, a three-color signal R0, G0, B0 read based on the spectral characteristics of the CCD 210 by NTSC.
And an input masking unit for converting into three color values R, G, B in a standard color space such as.

Reference numeral 303 denotes a luminance-density conversion unit for converting the R, G, B luminance signals into density signals C0, M0, Y0.
An output masking unit 304 changes the three-color density signals C0, M0, and Y0 to output signals C, M, and Y that match the spectral characteristics of the toner of the printer, and generates a portion where the three colors are output in black as Bk. , 305 is a printer 500
Density correction unit 306 for performing density conversion according to the output characteristics of
Is a scaling unit capable of performing a predetermined scaling, and 307 is a spatial filter.

In the above configuration, the output masking section 30
4 is one color for one scan, and the signal for one color from the output masking unit 304 is processed by a known density correction unit 305, scaling unit 306, and spatial filter 307, and the printer 200 is processed. And the desired print output is performed.

Reference numeral 311 denotes an editing processing unit which edits an input image when performing editing processing such as color conversion. More specifically, after processing in the input masking 302, when processing is performed in the edit processing unit 311, first, the coordinate conversion circuit 308
Converts R, G, and B into three coordinate values of hue (H), saturation (S), and lightness (L), and converts H, S, and L into H ′, S according to a desired process. After changing to ', L', the coordinate inverse transform circuit 310 returns the coordinates to RY, G ', B' again.

The signal is output to the luminance-density conversion circuit 303. Subsequent processing is the same as when no editing processing is performed.

[Two-Color Processing] Further, in the embodiment of the present invention, when a full-color image is printed out as an image such as "two-color printing", instead of general full-color printing warpage, the following is performed. The “two-color printing” control, which will be described in detail, is performed. As a result, a very easy-to-read print output result is obtained.

An example of processing for converting a full-color image into an image such as "two-color printing" will be described with reference to FIG. FIG. 3 is a diagram for explaining control in the case where a full-color image in this embodiment is converted into an image such as "two-color printing".

In this case, for example, when one color other than black is specified as (H1, S1, L1), in this example, the input image is (H0, S0, L0) and the output image is (H, S1). ,
L), H is equal to H1, and L and S are converted and output according to the conversion formula shown in FIG. Hereinafter, a case where H0 = 0, that is, “red” will be described as an example.

In the RGB space, the most vivid “red”, that is, (255, 0, 0) corresponds to the point of (S, L) = (255, 128) on the SL plane.

An example of the result of the inventor's investigation when (S1, L1) is designated as the "color after change" will be described below.

In the case of L1 ≧ 128 (light color) It becomes natural in appearance that the brightest color in the document is replaced with the designated color.

In the case of L1 <128 (dark color) If (S, L) = (255, 128) is converted to (S1, L1), the color becomes fogged in the thin part, and the part that is crushed becomes large. It becomes unnatural. On the other hand, replacing (255, L1) with (S1, L1) results in a better image.

The conversion equation is not limited to this example.

FIG. 4 shows an outline of the printing process in the present embodiment including the printing output process related to the two-color printing described above. FIG. 4 is a flowchart showing a printing process according to the embodiment.

In step S1, an image read by the scanner 200 is input. In step S2, whether the image is set to a mode for performing a normal full-color printing process or is set to a print output mode for two colors. Find out what. The output mode is set from an operation panel (not shown). If the normal print output mode has been designated, the process proceeds to step S3, and normal print output processing using another configuration not via the image editing unit 311 shown in FIG. 2 is performed.

On the other hand, when the print output in two colors is designated, the above-described image processing using the image editing unit 311 shown in FIG. 2 is performed. First, in step S5, RGB → HSL
An input image (Hin, Sin, Li
For n), RGB → HSL conversion is performed. Then, in step S6, it is checked whether or not (Lin <128) in the input image (Hin, Sin, Lin). That is, when one color other than black is designated as (H1, S1, L1), the input image is (H0, S0, L0) and the output image is (H, S, L).
Then, H = H1 is kept constant, and the above determination is made for L. For example, taking the case of H0 = 0, that is, “red”, in the RGB space, the most vivid “red”,
That is, (255, 0, 0) becomes (S,
L) = (255, 128), and Li when (S1, L1) is designated as the “color after change”
n will be determined.

If Lin <128 in step S6, the process proceeds to step S7, otherwise, the process proceeds to step S7.
Then, as described above, arithmetic processing is performed by the calculation formula shown in FIG. This arithmetic processing is performed by the arithmetic processing unit 309
Do with. Then, after executing this calculation process, the process proceeds to step S9, and in step S9, the HSL → RGB conversion unit 3
The HSL → RGB conversion is performed by the CPU 10 and restored to RGB data again, and the luminance / density conversion unit 303 in step S10 is performed.
To perform the brightness-density conversion processing. Then step S11
As shown in FIG. 2, a normal image output process by the components shown in FIG. 2 is performed, and a print output process by the printer 500 is performed in step S12.

As described above, by using the (H, S, L) coordinate system, what kind of designated color (H1, S1, L
It is also possible to easily generate a “two-color printing” image for 1).

(Other Embodiments) In the above-described first embodiment of the present invention, the converted color is a color that can be expressed by a single color or two colors of toner, that is, R, G, B, and C. ,
If the color is any one of M and Y, one or two colors for the remaining color formation in the image formation by the printer 500 are performed.
The example in which the output image is obtained earlier by omitting the sequence for the color has been described. However, the present invention is not limited to the above examples, for example, even in such a case,
Since the spectral characteristics of the toner are non-linear, if the same output masking 304 is performed as in the normal full-color processing, an output signal is slightly generated for an unnecessary color (for example, C, Y when magenta is specified).

Therefore, in such a case, the output masking section 304 may be controlled so that unnecessary components are not output (set to 0). By performing such control, unnecessary color components are not printed out, and the quality is further improved. At this time, C, which is not simply set to 0, but is output to a color that is not necessary (M, Bk in the above example),
An operation for supplementing the Y component may be added. By performing such control, a higher quality print output can be obtained.

In performing the above control, the CPU which performs various controls (not shown) controls the image output from the output masking section 304 so that the recording color of the printer 200 matches.

[0040]

Further, another embodiment of the present invention is applicable to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.). , A copying machine, a facsimile machine, etc.).

Another object of the present invention is to supply a storage medium storing a program code of software for realizing the functions of the above-described embodiments to a system or an apparatus, and to provide a computer (or CPU) of the system or the apparatus.
And MPU) read and execute the program code stored in the storage medium.

In this case, the program code itself read from the storage medium implements the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.

As a storage medium for supplying the program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD
-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also an OS (Operating System) running on the computer based on the instruction of the program code. ) May perform some or all of the actual processing, and the processing may realize the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, based on the instructions of the program code, It goes without saying that the CPU provided in the function expansion board or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

When the present invention is applied to the storage medium, the storage medium may store the program code for realizing the functions described above in the storage medium.

[0047]

As described above, according to the present invention, a desired output can be obtained for any original by generating a "color-printed" image by calculating the hue, saturation, and brightness. Become like

By designating two-color printing of a specific color, it is possible to achieve high quality and quick output.

[0049]

[Brief description of the drawings]

FIG. 1 is an overall view of a color copying machine according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a detailed configuration of a signal processing unit illustrated in FIG. 1 according to the embodiment of the present invention.

FIG. 3 shows a full-color image according to the embodiment as “2”.
It is a figure for explaining control at the time of converting into an image like "color printing."

FIG. 4 is a flowchart illustrating a printing process according to the embodiment.

[Explanation of symbols]

 Reference Signs List 200 printer 201 image scanner 202 digitizer 203 platen glass 204 document 205 halogen lamp 206, 207 mirror 208 lens 209 signal processing unit 210 CCD 301 shading correction unit 302 input masking unit 303 brightness / density conversion unit 304 output masking unit 305 density correction unit 306 Magnifying unit 307 Spatial filter 308 RGB → HSL conversion unit 309 Operation processing unit 310 HSL → RGB conversion unit 311 Editing processing unit

Claims (8)

[Claims] 1. A conversion unit for performing coordinate conversion of an input image signal of a plurality of colors into a signal in a color space including three coordinates of hue, saturation, and lightness, and performing a predetermined arithmetic processing on the signal subjected to coordinate conversion by the conversion unit. Processing means for applying, and inverse conversion means for inversely converting a signal processed by the processing means into a signal of an original color space before conversion by the conversion means, wherein the processing means An image processing device capable of being converted into an image represented by color shading. 2. The image processing apparatus according to claim 1, wherein said processing means is capable of converting the input image into an image represented by two shades of a specified color other than black and black. . 3. An output unit for outputting an image in a frame-sequential manner for each color, wherein the output unit outputs another unnecessary color component when the processing unit converts the image into a two-color grayscale image. 3. The image processing apparatus according to claim 1, wherein the procedure can be omitted. 4. A conversion step of performing coordinate conversion of an input image signal of a plurality of colors into a signal of a color space including three coordinates of hue, saturation, and lightness, and performing a predetermined arithmetic processing on the signal subjected to the coordinate conversion in the conversion step. And a reverse conversion step of reversely converting the processing signal from the processing step into a signal in the original color space before the conversion in the conversion step.In the processing step, the input image is processed by the arithmetic processing. An image processing method characterized in that it can be converted into an image represented by two shades of color. 5. The image processing method according to claim 4, wherein in the processing step, the input image can be converted into an image represented by two shades of a specified color other than black and black. . 6. An output step of outputting an image in a frame-sequential manner for each color, wherein the output step outputs another unnecessary color component when the image is converted into a two-color gray-scale image in the processing step. The image processing method according to claim 4, wherein a procedure can be omitted. 7. A computer program for realizing a function for realizing the steps according to claim 4. Description: 8. A storage medium storing a computer program for realizing the function for realizing the steps according to claim 4. Description: